The EMP sensor kit was developed as a cost effective alternative to more expensive lightning detectors on the market. It boasts a fast response time and also allows adding an experimental input filter (a low-pass LC circuit which is normally not populated). Compared with commercial sensors, this unit is more sensitive, and allows repairs using readily available parts.

The design employed is essentially a VLF broadband receiver. The heart of the circuit is a Darlington pair that provides an open-collector output capable of safely sinking several mA. When a stroke is detected the output momemtarily shorts to ground. Designed to be used with the X1W-1 or X1W-2 EMP interface, the output is fed to a simple 1-Wire counter which is then read by the system periodically.

Other than the usual assembly tools for kits, you will also need a hacksaw, drill and a high-wattage soldering iron or gun. The latter will only be used to sweat solder the copper antenna pipe to the PC board. A small 15W-25W iron will still be required to solder all other components on the PC board.

Firmware/software support for this kit is given below:

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Latest changes and other information on the X1W-4 is available at either of the following two sites:

The T-238, T-238+, X1W-1, X1W-2 and X1W-4 are discussed on the Weather Special Interest Group (WXSIG). You can join WXSIG via the web by clicking here.


The Tucson Amateur Packet Radio X1W-4 kit was made possible by the efforts of:

John Bennett, N4XI – Conceptual and PCB Design
John Koester, W9DDD – Project Manager
Steve Bible, N7HPR – Assistant Project Manager
Joe Borovetz, WA5VMS – Parts Liaison